Whether or not a teacher is good (and the right way to determine that) is the major issue in education today. How to figure out how to incorporate test scores, teachers’ classroom manner, and any number of other factors into a holistic measurement of teacher ability has stymied everyone. But the end result of a three-year study by the Gates Foundation in schools around the country claims to have an answer:
The most reliable way to evaluate teachers is to use a three-pronged approach built on student test scores, classroom observations by multiple reviewers and teacher evaluations from students themselves. …
Researchers videotaped 3,000 participating teachers and experts analyzed their classroom performance. They also ranked the teachers using a statistical model known as value-added modeling, which calculates how much an educator has helped students learn based on their academic performance over time. And finally, the researchers surveyed the students, who turned out to be reliable judges of their teacher’s abilities.
They then took students, randomized them, and assigned them to different teachers. Teachers who had been good one year managed to replicate the results, and their students not only did better on standardized tests but also "complicated tests of their conceptual math knowledge and reading and writing abilities."